The invention relates to a process for carrying out a chemical equilibrium reaction by introducing one or more reactants in the gaseous phase into a reaction zone comprising one or more fixed beds of catalyst particles having interstices therebetween, at least a portion of said catalyst particles comprising a catalyst for said chemical equilibrium reaction.
In order to increase the product yield it is desirable to remove the product from the reaction zone effluent and to recycle unconverted starting compounds to the reaction zone. According to a method known from European patent specification No. 0 027 329 this is effected by condensing the product on cooling surfaces. However, in those cases where the position of the equilibrium reaction is unfavorable at the temperature at which the reaction is carried out the products of the equilibrium reaction will have a low concentration in the reaction mixture. In such cases cooling surfaces must be very large and have a relatively low temperature. Furthermore, the cooling surfaces simultaneously cool the unconverted reactants, so that much reheating is required before they can be recycled to the reaction zone. Moreover, the amounts of unconverted starting compounds to be recycled are usually very large, requiring substantial compression energy.
It is an object of the present invention to avoid recycling of unconverted reactants and to avoid using the cooling surfaces as described hereinbefore.